Spending the night in a temple- Being the HQ for the Buddhist school, there were a ton of temples everywhere. About 50 of them offer rooms for guests to spend the night and the monks act as the hotel staff. Here is the temple we stayed at.
Our room: When we first arrived at the Eikoin Temple, 1 of the many young monks standing around the temple led us to our room on the second floor. The room actually consisted of 3 rooms with sliding doors that we could close if we wanted to. We ate our meals in one room and we slept in the other two rooms. The rooms were very Japanese, with tatami floors, a small table with green tea in the corner, our futons (beds) folded in the closet, and a beautiful view of the Japanese garden outside. The onsen (public bath) was located on the first floor of the temple. So we all took a shower and bath with the other guests during the evening (it's strange, but this feels normal to us now!)
Dinner: The temple stay is a bit expensive, $100 a person, but it does include 2 meals. We were told to be in our rooms at 5:30pm for our dinner to be served. The monks prepared a huge meal for us then set it out in our room. The food was all vegetarian; they don't eat any meat, fish, onions or garlic. At first we thought that the food wasn't that bad, but the more we ate it, the more we realized how strange the textures and tastes were!
Our meal consisted of white rice, cold soba noodles, veggie tempura (this was really good), cold sweet beans, miso soup with seaweed, sesame tofu, a Japanese pear, and a plate of something we really had no idea what it was...it literally absorbed water like a sponge and had no flavor! While we were eating, the monks were in the other 2 rooms preparing our beds.
Morning Prayer Services: Because temple stays are intended for religious pilgrims, we were expected to observe the Buddhist prayer services the next morning. At 6:30 am, a monk came to our room and led us and about 30 other guests to the temple's main hall. We all sat on the floor here for about 30 minutes listening to about 8 monks pray and chant sutras from a venerable scroll. Some of the Japanese guests went to the front and did a prayer as well, but others like us just watched.
Here is a video of us trying to be discreet and videotape the prayer service:
After the prayer service, we moved to a smaller building where two monks performed a ritual in which they built a bonfire in a huge burner, and then read prayers for health and prosperity. Here is another video:
Breakfast: After the prayer service, we went back to our room to find breakfast ready and waiting for us. We had miso soup, white rice, green beans with a white gooey sauce, and "sponge" again. Not too great, but edible for the most part.
Staying the night in the temple was a great experience! It was really interesting for us to not only see this part of the Japanese culture, but also be able to participate in it.
Sights around Koyasan-
Kongobuji Temple and Rock Garden: This temple, built in 1593, is the headquarters of 3600 Shingon temples in Japan. Each room had ornate paintings on the doors that told a different story, unfortunately we weren't allowed to take pictures.
We really enjoyed the huge rock garden here. It is actually the largest in Japan and has 140 granite stones arranged to look like a pair of dragons emerging from clouds to protect the temple.
We really enjoyed the huge rock garden here. It is actually the largest in Japan and has 140 granite stones arranged to look like a pair of dragons emerging from clouds to protect the temple.
Garan: This is an area filled with many temples and pagodas, which are known as some of the most sacred sites in Koyasan.
Okunoin Graveyard: Believe it or not, walking through this graveyard was the highlight of our time in Koyasan...it was beautiful and extremely peaceful. This cemetery has more than 500,000 grave stones, the oldest dating to the 9th century! This is actually the most desirable cemetery to be buried in in the country because the Japanese believe that anyone buried here is in the pole position for when the future Buddha returns to the world. For centuries, anyone who is anyone has been buried here, even if its only a lock of hair or a tooth or two. The people who founded Nissan and Toyota are even buried here! 
We walked along a 2 km winding path that was lined with enormous cypress trees. The cemetary was very serene and filled with so much history. We did come across some grave stones that were wearing make-up and clothes...this we found pretty funny!
Torodo Lantern Hall: At the end of the 2 km path in the graveyard was a lantern hall filled with about 21,000 lanterns! This is why we were interested in coming to Koyasan initially. It was unbelievable the amount of lanterns they had here. We even came back again to see the lanterns at night. There are supposedly 2 lanterns here that have burned uninterrupted for a thousand years! After looking at all the lanterns, we discovered a room filled with thousands of really small Buddha statues. 
